Learn About 401(k) Loans and Associated Costs

What a 401(k) Loan Actually Is and How It Works

A 401(k) loan is when you borrow money from your own retirement savings account while you're still working at the company that sponsors the plan. This isn't the same as taking a withdrawal. When you withdraw money, it's gone from your retirement account permanently. With a loan, you're borrowing against your balance and agreeing to pay it back with interest over a set period of time.

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The basic mechanics work like this: You request a loan from your plan administrator. The administrator calculates how much you're allowed to borrow based on plan rules and your account balance. Once approved, you receive a lump sum of cash. Then you begin repaying the loan in installments, typically through payroll deductions. The interest you pay goes back into your own 401(k) account, not to a bank or lender.

Not all 401(k) plans allow loans. According to the IRS, roughly 70% of 401(k) plans permit borrowing, but this varies significantly by employer and plan type. Some employers choose not to offer loan provisions at all, while others have restrictive rules about how much you can borrow or how quickly you must repay.

The IRS sets some basic rules that most plans follow. You generally cannot borrow more than 50% of your vested account balance or $50,000, whichever is less. If your account balance is $60,000, you could borrow up to $30,000. If your balance is $80,000, you're still capped at $50,000. The loan must be repaid within five years, unless the money is used to buy a primary residence—in which case the repayment timeline can extend longer.

Practical Takeaway: Before considering a 401(k) loan, check your plan documents or contact your HR department to confirm whether loans are even permitted under your specific plan. If they are, get the exact borrowing limits and repayment terms that apply to your situation.

The Direct Costs: Interest Rates and Loan Fees

When you take a 401(k) loan, you pay interest just like you would with any loan. However, the interest rates for 401(k) loans are often lower than personal loans or credit cards. The interest rate is typically set at the prime rate plus a percentage point or two. As of 2024, prime rate hovers around 8.5%, so a 401(k) loan might carry an interest rate between 8.5% and 10.5%, though this varies by plan and lender.

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What makes 401(k) loan interest different from other loans is where it goes. When you pay interest on a personal loan or credit card, that money goes to the bank or credit card company. With a 401(k) loan, the interest you pay goes back into your own retirement account. This is sometimes presented as an advantage, but it's important to understand what this really means for your finances.

Beyond interest, many plans charge administrative or origination fees to set up the loan. These fees typically range from $50 to $200, though some plans charge more. A few plans charge annual maintenance fees while the loan is outstanding. You might also face processing fees or fees if you want to pay off the loan early. Some plans charge nothing; others charge several hundred dollars in combined fees.

Let's look at a concrete example. Suppose you borrow $20,000 at 9% interest over five years with a $100 origination fee. Your monthly payment would be approximately $415. Over the five-year period, you'd pay about $4,900 in total interest, plus the initial $100 fee. That $5,000 goes back into your 401(k), but it represents real money leaving your paycheck.

Different plans set rates differently. Some use a fixed rate based on the prime rate at the time you take the loan. Others use a variable rate that adjusts periodically. You should ask your plan administrator exactly how your rate is calculated and whether it could change during the loan period.

Practical Takeaway: Request a loan calculation from your plan administrator that shows the exact interest rate, all fees, and the monthly payment amount before you commit. Compare this total cost to other borrowing options like a personal loan or line of credit to see whether a 401(k) loan is actually cheaper.

The Hidden Costs: Opportunity Loss and Market Growth

This is where 401(k) loans get complicated, and it's often where people underestimate the real cost. When you borrow $20,000 from your 401(k), that $20,000 is no longer invested in the stock market or bonds or whatever your account holds. While you're repaying the loan, that money isn't growing through investment returns.

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This matters because retirement accounts are designed to grow over time through compound interest. If your 401(k) historically averages 7% annual returns, and you borrow $20,000, that money is generating 0% return while it's out of the account. Meanwhile, you're paying 9% interest on the loan. The math here actually works against you: you're losing the opportunity to earn investment gains while paying interest to yourself.

Consider this scenario over ten years. Suppose your 401(k) would normally earn 7% annually. If you borrow $20,000 and repay it over five years, that money sits idle during the loan period instead of growing. The difference between what the $20,000 would have grown to (about $39,500 after ten years at 7% returns) and what you actually have when you repay it can be substantial. You'd have roughly $15,000 less in retirement savings than if you'd never borrowed at all, even though you paid back the principal plus interest.

Market timing also plays a role. If you borrow money during a period when the stock market performs poorly anyway, the opportunity loss feels less dramatic. But if you borrow just before the market enters a strong growth period, you miss out on significant gains. You can't predict market performance, which means you can't know in advance how costly your loan will be in terms of missed growth.

There's another dimension to this: while you're repaying the loan, you're contributing money to your 401(k) that might otherwise go toward additional retirement savings or debt payoff. If you're paying $415 per month on a 401(k) loan, that's $415 you're not putting toward an emergency fund, paying down credit card debt, or funding other investments.

Practical Takeaway: Ask your plan administrator or a financial advisor to calculate the projected growth of the amount you'd borrow over the loan period. Compare that projected growth to the interest you'd pay. This gives you a realistic picture of the true cost beyond just the interest rate.

Tax Implications If You Leave Your Job

The rules around 401(k) loans change significantly if you leave your job—either voluntarily or involuntarily. This is one of the most important costs to understand, and it's often overlooked when people take 401(k) loans.

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Here's what happens: If you borrow money from your 401(k) and then leave your job, your employer's plan typically requires you to repay the entire loan balance within a specific timeframe—usually 30 to 90 days, though it varies by plan. If you don't repay it within that window, the IRS treats the outstanding loan balance as a distribution (a withdrawal) from your retirement account.

When a loan is treated as a distribution, two major tax consequences occur. First, you owe income tax on the full amount of the loan that wasn't repaid. If you borrowed $20,000 and couldn't repay it before the deadline, you'd owe federal income tax on the full $20,000 at your marginal tax rate. If you're in the 22% tax bracket, that's $4,400 in taxes. Some states also charge state income tax on top of this. Second, if you're under age 59½, you also face a 10% early withdrawal penalty on that $20,000, which is another $2,000.

So in this scenario, you'd owe approximately $6,400 in combined federal and penalty taxes on money you already borrowed and presumably spent. This is a substantial hidden cost that makes 401(k) loans risky if your employment situation is uncertain. Even if you think you'll stay in your job,